This invention relates generally to speed reducers and more particulary but not by way of limitation to an improved speed reducer box used in driving an oil pump jack.
Heretofore oil pump jacks have been driven by a drive motor or the like using a gear box for reducing the speed between the drive motor and the pump jack. Under normal pumping conditions the average horse power requirement of the drive motor is between 20 to 65 HP at speeds of 400 to 1200 rpm. The gear box reduces the speed a ratio of approximately 30 to 1. Due to the high torque reversal between the lifting of the polish rod load and the counterweight load, the gear box is subjected to a gear slap. The gear slap causes accelerated wear of the gear teeth thereby greatly reducing the life of the gear box.
Pump jacks have used chain driven speed reducers for reducing the speed from a drive motor but none of the prior art speed reducers disclose the novel features of the subject speed reducer box and its advantages as disclosed herein.